1. Field of the Invention
The present invention relates to a conductive thermoplastic resin, and especially relates to a conductive polyphenylene ether-polyamide blend.
2. Brief Description of the Related Art
Poly(phenylene ether) resins (referred to hereafter as “PPE”) are commercially attractive materials because of their unique combination of physical, chemical, and electrical properties. Furthermore, the combination of these resins with polyamide (PA) resins into compatibilized blends results in additional overall properties such as chemical resistance, high strength, and high flow. Examples of such compatibilized blends can be found in U.S. Pat. Nos. 4,315,086 (Ueno, et al); 4,659,760 (van der Meer); and 4,732,938 (Grant, et al). The properties of these blends can be further enhanced by the addition of various additives such as impact modifiers, flame retardants, light stabilizers, processing stabilizers, heat stabilizers, antioxidants and fillers.
The physical properties of PPE/polyamide blends make them attractive for a variety of end-use articles, for example, in the automotive market, for various exterior components. Dimensional behavior of these components is critical due to the differences in coefficient of thermal expansion, which can be improved by adding fillers (organic/inorganic) as known to those skilled in the art.
U.S. Pat. No. 5,591,382 to Nahass et al., discloses a polymeric composition comprising carbon fibrils, at least a portion of which are in the form of aggregates, wherein, as measured on an area basis, substantially all of the aggregates are less than about 35 {circumflex over (1)}¼ in diameter. The polymeric composition is prepared by combining the carbon fibrils with a polymeric material, mixing the combination to distribute the fibrils in the polymeric material and applying shear to the combination to break down the aggregates until substantially all of the aggregates are less than about 35 {circumflex over (1)}¼ in diameter. Nahass et al. teach the use of a lower loading of the conductive fibrils in order to achieve a certain conductivity while retaining better impact performance compared to carbon black or carbon fibers.
Although numerous PPE/polyamide compositions having a variety of properties are available, compositions having alternative properties are continuously sought in the industry.